Located in the heart of the University's medical complex, the Small Animal Cancer Imaging Core provides intellectual and physical resources devoted to magnetic resonance imaging (MRI), positron emission tomography, (PET), and optical tomography (OT) directed toward small laboratory animals such as hamsters, rats and mice. MRI resources include a high-field 11.7 tesla multinuclear scanner, one of only a few worldwide, and three 4.7 tesia multinuclear scanners. Recent upgrades of electronics consoles, gradient coils, and gradient power supplies, have restored these instruments to state-of-the-art quality. The PET/CT Component is centered on two microPET scanners from Siemens Medical, including a newly acquired, state-of-the-art Inveon microPET-CT instrument. Two cyclotrons and an associated radiochemistry laboratory are connected to the PET facility via a pneumatic tube system and a small-bore gas line for transport of liquid (contained in syringes) and gaseous radiopharmaceuticals. Both MRI and PET scanners offer sensitivity and resolution optimized for small-animal research. Additional resources for support of small-animal imaging include housing, physiologic support and monitoring equipment, surgical procedure rooms, wet chemistry laboratories, and data analysis and archival systems. The Core provides Siteman Cancer Center members with the latest in small-animal MRI, PET, and OT capabilities. Highly skilled staff members are available to assist, advise, and collaborate on projects of interest to Siteman members. For the last five years, the Small Animal Cancer Imaging Core has been supported primarily through the National Cancer Institute (NCI) Small Animal Imaging Resource Program (SAIRP). Washington University Small Animal Imaging Resource (WUSAIR) was one of the original five SAIRP centers, established in 1999, and received ~$3 million in total support from 2004 to 2009.